Nothing raises nationalist hackles in Mexico like talk of the United States military acting south of the border or targeting Mexican citizens.

So it didn’t exactly help Secretary of State Rex Tillerson’s visit to Mexico City when President Trump on Thursday described stepped-up deportations – which would likely hit tens of thousands undocumented Mexicans living in the US – as a “military operation.”

Department of Homeland Security Secretary John Kelly, who joined Mr. Tillerson for high-level meetings in the Mexican capital this week, was quick to try to tamp down the growing angst.

“There will be no – repeat, no – use of military force in immigration operations,” Mr. Kelly told his Mexican hosts. That clarification followed Kelly’s equally emphatic assurance earlier Thursday that “there will be no – repeat, no – mass deportations.” Everything Homeland Security and its civilian officers do will be “according to human rights and the legal justice system of the United States.”

The Tillerson-Kelly visit to Mexico was billed as an effort to smooth out relations that got off to a rocky start, prompting Mexican President Enrique Peña Nieto to cancel a White House meeting earlier this month.

But it’s hard to see that changing any time soon, with Trump’s military reference further troubling relations already soured by the new immigration orders and plans to make Mexico pay for a border wall. The disparity between the president’s rhetoric and his cabinet members’ assurances left Mexican officials confused.

More broadly, the visit showcased US-Mexico relations as a first test of how Trump’s “America First” vision will play out in US foreign policy as the administration moves beyond the slogan to implementation.

“It’s like at the start of a boxing match when the two fighters are just making the rounds, circling and getting to know each other,” says Jorge Chabat, an expert in security issues at Mexico City’s Center for Research and Teaching in Economics. “This is just the beginning of the fight, this is going to be a long and not-so-easy negotiation.”

Test of 'America first'

For some, the path ahead depends largely on Trump and how he translates campaign promises into actions.

“Trump based his campaign on immigration and trade, so it’s no surprise he’s addressing those issues,” says Michael Shifter, president of the Inter-American Dialogue in Washington. “But the question now is how he juggles political realities with long-term national interests. Is the vision of ‘national interests’ one that is based on frustration and emotions, or is it one that is based more on the evidence and facts?”

For example, more than 5 million US jobs depend on the North American Free Trade Agreement and good trade relations with Mexico. New tariffs on Mexican products would also mean higher consumer prices in the US. In recent years, Mexico has stepped up cooperation with the US on anti-terror initiatives and on Central American migrants making their way to the US-Mexico border.

“Those are just some of the ways that retreat from good relations with Mexico would hurt the US – and hurt the people who supported Trump,” Mr. Shifter says.

Shared interest in Mexico's stability

What worries Mexicans, Mr. Chabat says, is that Trump appears to be retreating from decades of US policy – followed by both Republican and Democratic presidents – that saw stability and growing prosperity in Mexico as a vital US interest.

“The US has understood since the 1930s the importance of having stability in Mexico,” Chabat says. “And the growing cooperation between the two countries since then indicates the US side realized its interests extended beyond terrorism and stopping drug traffickers. American interests are not as simple as jobs on US territory,” he adds, “they’re also about economic conditions in Mexico.”

Not least of Mexico’s concerns is that deportations would eat into the estimated $25 billion in annual remittances that flow from the US to Mexico. Not all that comes from undocumented workers, but the impact on Mexican family incomes could still be significant.

Shifter says there’s no question US-Mexico relations have sustained some damage and will take time to be “put back on the rails.”

At such a time of uncertainty, Mexicans don't know whether to believe reports that the US could redirect its security assistance to Mexico to pay for the wall or that it could dump undocumented immigrants (not just Mexicans) in Mexico.

Even if these ideas never come to fruition, they are raising questions about the direction of relations with the US and prompting consideration of retaliatory measures in response. The result is a more adversarial environment.

“The risk is that all of the very real progress of recent years will be set back,” Shifter says, “and that won’t be good for either country.”